cat, owl, deer, elk

…Complicated machine ciphers are not the only way of sending secure messages. Indeed, one of the most secure forms of encryption used in the Second World War was also one of the simplest.

The son of a Protestant missionary, <Philip> Johnston had grown up on the Navajo reservations of Arizona, and as a result he had become fully immersed in Navajo culture. He was one of the few people outside the tribe who could speak their language fluently, which allowed him to act as an interpreter for discussions between the Navajo and government agents. His work in this capacity culminated in a visit to the White House, when, as a nine-year-old, Johnston translated for two Navajos who were appealing to President Theodore Roosevelt for fairer treatment for their community. Fully aware of how impenetrable the language was for those outside the tribe, Johnston was struck by the notion that Navajo, or any other Native American language, could act as a virtually unbreakable code. If each battalion in the Pacific employed a pair of Native Americans as radio operators, secure communication could be guaranteed.

Before training could begin, the Marine Corps had to overcome a problem that had plagued the only other code to have been based on a Native American language. In Northern France during the First World War, Captain E. W. Horner of Company D, 141st Infantry, ordered that eight men from the Choctaw tribe be employed as radio operators. Obviously none of the enemy understood their language, so the Choctaw provided secure communications. However, this encryption system was fundamentally flawed because the Choctaw language had no equivalent for modern military jargon. A specific technical term in a message might therefore have to be translated into a vague Choctaw expression, with the risk that this could be misinterpreted by the receiver.

The same problem would have arisen with the Navajo language, but the Marine Corps planned to construct a lexicon of Navajo terms to replace otherwise untranslatable English words, thus removing any ambiguities. The trainees helped to compile the lexicon, tending to choose words describing the natural world to indicate specific military terms. Thus, the names of birds were used for planes, and fish for ships. Commanding officers became ‘war chiefs’, platoons were ‘mud-clans’, fortifications turned into ‘cave dwellings’ and mortars were known as ‘guns that squat’.

Navajo codewords for planes and ships

Fighter plane Hummingbird Da-he-tih-hi
Observation plane Owl Ne-as-jah
Torpedo plane Swallow Tas-chizzie
Bomber Buzzard Jay-sho
Dive-bomber Chicken hawk Gini
Bombs Eggs A-ye-shi
Amphibious vehicle Frog Chal
Battleship Whale Lo-tso
Destroyer Shark Ca-lo
Submarine Iron fish Besh-lo

Even though the complete lexicon contained 274 words, there was still the problem of translating less predictable words and the names of people and places. The solution was to devise an encoded phonetic alphabet for spelling out difficult words. For example, the word ‘Pacific’ would be spelled out as ‘pig, ant, cat, ice, fox, ice, cat’, which would then be translated into Navajo as bi-sodih, wol-la-chee, moasi, tkin, ma-e, tkin, moasi.

The Navajo alphabet code

A Ant Wol-la-chee N Nut Nesh-chee
B Bear Shush O Owl Ne-ahs-jsh
C Cat Moasi P Pig Bi-sodih
D Deer Be Q Quiver Ca-yeilth
E Elk Dzeh R Rabbit Gah
F Fox Ma-e S Sheep Dibeh
G Goat Klizzie T Turkey Than-zie
H Horse Lin U Ute No-da-ih
I Ice Tkin V Victor A-keh-di-glini
J Jackass Tkele-cho-gi W Weasel Gloe-ih
K Kid Klizzie-yazzi X Cross Al-an-as-dzoh
L Lamb Dibeh-yazzi Y Yucca Tsah-as-zih
M Mouse Na-as-tso-si Z Zinc Besh-do-gliz

The impenetrability of the Navajo code was all down to the fact that Navajo belongs to the Na-Dene family of languages, which has no link with any Asian or European language. For example, a Navajo verb is conjugated not solely according to its subject, but also according to its object. The verb ending depends on which category the object belongs to: long (e.g. pipe, pencil), slender and flexible (e.g. snake, thong), granular (e.g. sugar, salt), bundled (e.g. hay), viscous (e.g. mud, feces) and many others. The verb will also incorporate adverbs, and will reflect whether or not the speaker has experienced what he or she is talking about, or whether it is hearsay. Consequently, a single verb can be equivalent to a whole sentence, making it virtually impossible for foreigners to disentangle its meaning.

Altogether, there were 420 Navajo code talkers. Although their bravery as fighting men was acknowledged, their special role in securing communications was classified information. The government forbade them to talk about their work, and their unique contribution was not made public. Just like Turing and the cryptanalysts at Bletchley Park, the Navajo were ignored for decades. Eventually, in 1968, the Navajo code was declassified, and the following year the code talkers held their first reunion. Then, in 1982, they were honoured when the US Government named 14 August ‘National Navajo Code Talkers Day’. However, the greatest tribute to the work of the Navajo is the simple fact that their code is one of very few throughout history that was never broken.

Simon Singh,

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